Hiraizumi Fujiwara

The Hiraizumi Fujiwara, also called the Eastern Fujiwara, was a Japanese samurai clan hailing from northern Japan. The north of Japan was split in half between the Hiraizumi Fujiwara to the northeast and the Kubota Fujiwara (also called "Western Fujiwara") to the northwest. In 1177 a civil war divided the two Fujiwara clans and the Hiraizumi were the ones who would suffer from it, and they would also suffer a string of losses to the Kamakura Minamoto daimyo Minamoto Yoritomo in the 1180s. They made a brief alliance which broke down when the emperor declared the Minamoto enemies of the state and a storm brewed. The Minamoto were forced to defeat all of their former allies in a large war.

History
The Hiraizumi branch of the Fujiwara family was so-called because it originated in the city of Hiraizumi in northern Japan. The Fujiwara had reigned for years as regents of the Heian empire, but in 1175 their yoke was overthrown by ambitious daimyo Taira Kiyomori, who made the Emperor his puppet. Up north, the Fujiwara schemed their comeback to power while the Minamoto and Taira battled down south. The Hiraizumi and their sister branch the Kubota Fujiwara were peaceful at first, with Hiraizumi  daimyo  Fujiwara Hidehira having an understanding with his relative Fujiwara Motofusa, but in 1177 peace was shattered when a family dispute turned into an armed conflict. The whole of the Fujiwara clan was threatened as their assets in central and southern Honshu were either defeated or turned into vassals by the Kamakura Minamoto, who slowly rose to prominence. The Hiraizumi had one army in the center of Japan, led by  daimyo  Fujiwara Kunihira, who became the new clan head after the death of Hidehira of natural causes in 1184. This army was eliminated in Shimosa Province in 1186 by the Minamoto  daimyo  Minamoto Yoritomo, who was determined to blunt their advance and counterattack to control northern Japan. The Hiraizumi leader Fujiwara Chikakage decided to make peace, and did so, and fought against the Kubota and some other clans. But by the late 1180s he had attacked the Nitta and the Minamoto intervened on behalf of their allies, eliminating their armies on their own ground and forcing them to make peace again. The Minamoto also attacked the Kubota Fujiwara, and forced both clans to become vassals.

But in 1190, this fragile peace was broken when the Kubota Fujiwara attacked a Minamoto ally and when the Hiraizumi received the edict from the Emperor that the Minamoto were enemies of the state. The two clans again readied their arms to fight the Minamoto.